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Exhaust question


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I have a 04 23' LSV with the 340 Monsoon and the closed cooling option. I think I'm starting to experience hydro locking but not sure can some one explain how the manifolds/risers/flappers work. I have been fighting what I thought was a battery/starter/grounding/dirty connection issue. But I am beginning to think that it could be hydro locking itself. Thanks for all the help.

Joe

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The exhaust manifolds are water cooled due to the closed environment. Water is plumbed to circulate in the surrounding jacket to cool the manifold from the hot exhaust gases. The water is then plumbed to enter the elbow (riser) at a point below the level that would allow water to get back in to the exhaust manifold itself. The exact position of the exhaust gas / water mixing is critical to keep water from backing up in to the manifold. Camshaft characteristics and timing have an effect on this but the manufacturers have the design set for the cam in the engine itself. The flappers stop water from surging up the exhaust system during quick stops or other backwash conditions.

If everything is production and nothing is damaged, the probability of water backing up and hydrolocking the engine is not that high. I would look more at the items you mention, a dead cell in your battery is usually a good culprit. I would also look to make sure the head gaskets are sound. Check for water in the oil and water on the plugs to determine if there is any hydrolocking.

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I notice that typically activity around here is down during weekends, especially a long one like the past. Most people are doing weekend things, out on the water, outside projects, closing up the summer house...etc. Most of my questions get answered during the week once people return to work....

I'd give it a few more days, and have some patience. Closed cooling systems are not very common around here, especially on the monsoon. I dont know how to answer your question. I do have to ask tho...are you sure its a closed cooling system?

- Chad

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I'm pretty sure it is closed cooling. The heat exchanger has antifreeze in it and the flush kit (option) puts water in the raw water pick up then when flushing engine running is exited out the bottom of boat and some out the exhaust. Maybe that might help and totally understand the weekend business. Just tryin to figure this out. This is my first boat and know little about the Marine specific parts on the engine. Thanks again.

Joe

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The typical closed cooling is really only partially closed. It still uses raw water for the exhaust manifolds.

There have been some issues reported if/when the exhaust gaskets/rtv are losing seal & allowing water to leak back into the cylinders from the water jackets around the manifolds.

This typically happens in the rear cylinders in the case of rust/corrosion of the manifolds - or any cylinder for the bad gaskets/rtv.

Best bet to eliminate hydro-locking as a culprit is to do as tvano suggested & pull the plugs & see if you get water coming out - either just when you pull the plugs - or when crank the engine with the lanyard out (stops fuel & ignition). Be sure to have some rags/towels ready to catch any water spewing from the cylinders.

Edit - spelling.

Edited by wienrdog
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After the we burned up the starter (bendix would not actuate) and replaced it I pulled the plugs and the #5 hole poured out antifreeze. Looks like I have either a head gasket or a cracked head.

Thanks to everyone who responded.

Joe

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Anyone know where I can find the Indmar manual to tear this motor down? I want to know the Indmar specs to put it back together.

Indmar shop manuals are not available to the public, but a clymer book is available on amazon LINK

Hopefully just a head gasket, good luck.

-Chris

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Sucks about the manual. Got to say this is one useful site, I have received more that the $25 membership worth of advice so I decided to help out a sign up for the year. Thanks again. Joe

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Well started to tear down the motor and found that my cooling is completely closed, the system flow antifreeze through the manifolds. Raw water is only plumbed to the risers after the trans and oil cooler. After taking the manifold off I tore it apart and found a block off plate between the manifold and riser. Also looks like there is 2 gaskets (each side of the block off plate) that started to leak on the manifold side. That is at first glance how I think coolant is getting into the cylinder. Has anyone seen this before? I'd like to replace this plate anyone know where to find that at? My first call is going to be Skidim, any other places? Thanks again

Joe

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Not sure how hard it was spun over, but you should also check the connecting rod, they can get bent in a hydrolock condition. I assume your analysis that the water might be getting in to the combustion chamber via the manifold/riser plate leak is based on water found in the exhaust gas portion of the manifold itself. Thus water goes in to the combustion chamber via the exhaust port.

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It didn't get spin to hard before the starter bendix died, I don't think it hurt the bottom end. I found a pretty nice rust trail on the exhaust manifold and the gasket between the block off plate and manifold was notnin good shape. I put it back together yesterday and it held 30 psi of air pressure in the manifold just need to reinstall and see what happen next. Thanks Joe

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It didn't get spin to hard before the starter bendix died, I don't think it hurt the bottom end. I found a pretty nice rust trail on the exhaust manifold and the gasket between the block off plate and manifold was notnin good shape. I put it back together yesterday and it held 30 psi of air pressure in the manifold just need to reinstall and see what happen next. Thanks Joe

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It didn't get spin to hard before the starter bendix died, I don't think it hurt the bottom end. I found a pretty nice rust trail on the exhaust manifold and the gasket between the block off plate and manifold was notnin good shape. I put it back together yesterday and it held 30 psi of air pressure in the manifold just need to reinstall and see what happen next. Thanks Joe

Good deal. Glad to hear it help pressure. That is certainly a good sign. I'l also glad to hear someone supporting the crew and thinking it's more than worth the money! Rockon.gif This site had been worth way more than the price of membership to meas well!

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